Ki Strike (Innate): Every 8 seconds, Shen's next attack deals 15 +5/level (+3.5% of his maximum health) bonus magic damage, and every time an enemy champion attacks Shen with a basic attack, the cooldown is reduced by 2 seconds.
Ability Description Levelling up

Shen is one of The only tanks in game that base just about all of his moves on Ability power I have made a build that makes his moves very effetive for example vorpal blade, 1v1 comabt against just about any opponent can be easy with vorpal blade having small CD you can continuously heal yourself, Feint will eat about 3 or 4 attack, and Stand United Will just give your sheild that edge it needs to keep an Allie alive.